Though diabetes and depression each increase a woman's risk of death from cardiovascular disease, together they increase that likelihood nearly three times.
Depression and diabetes appear to be associated with a significantly increased risk of death from heart disease and risk of death from all causes over a six-year period for women, according to a report in the Archives of General Psychiatry.
Depression affects close to 15 million U.S. adults each year and more than 23.5 million U.S. adults have diabetes, according to background information in the article. Symptoms of depression affect between one-fifth and one-fourth of patients with diabetes, nearly twice as many as individuals without diabetes. Diabetes and its complications are leading causes of death around the world.
An Pan, PhD, of the Harvard School of Public Health, Boston, and colleagues studied 78,282 women aged 54 to 79 in 2000 who were participating in the Nurses' Health Study. The women were classified as having depression if they reported being diagnosed with the condition, were treated with antidepressant medications or scored high on an index measuring depressive symptoms. Reports of type 2 diabetes were confirmed using a supplementary questionnaire.
During six years of follow-up, 4,654 of the women died, including 979 who died from cardiovascular disease. Compared with women who did not have either condition, those with depression had a 44 percent increased risk of death, those with diabetes had a 35 percent increased risk of death and those with both conditions had approximately twice the risk of death.
When considering only deaths from cardiovascular disease, women with diabetes had a 67 percent increased risk, women with depression had a 37 percent increased risk and women with both had a 2.7-fold increased risk.
"The underlying mechanisms of the increased mortality risk associated with depression in patients with diabetes remains to be elucidated," the authors write. "It is generally suggested that depression is associated with poor glycemic control, an increased risk of diabetes complications, poor adherence to diabetes management by patients and isolation from the social network."
In addition, diabetes and depression are both linked to unhealthy behaviors such as smoking, poor diet and a sedentary lifestyle, and depression could trigger changes in the nervous system that adversely affect the heart.
"Considering the size of the population that could be affected by these two prevalent disorders, further consideration is required to design strategies aimed to provide adequate psychological management and support among those with longstanding chronic conditions, such as diabetes," the authors conclude.
Source: American Medical Association